In New Haven County, people are expected to live longer than the national average but lag behind the state average.

Males born in New Haven County in 2009 were expected to live to be 77, compared to 72.2 twenty years ago. Females will live longer but the increase over two decades was smaller. In New Haven County, females born in 2009 were projected to live to 81.8 years old, compared to 79.2 two decades years ago.

Nationally, males born in 2009 were expected to live 76.2 years and females 81.3.

Nationwide, women's life spans are improving at a much slower pace than men, and in hundreds of counties women are living shorter lives today than they did two decades ago, according to estimates by the IHME.

"It's tragic that in a country as wealthy as the United States and with all the medical expertise we have that so many girls will live shorter lives than their mothers," Dr. Ali Mokdad, the head of IHME's U.S. County Performance research team.

According to the study, women in Collier, Fla., are expected to live longest, at 85.8 years. In McDowell, W. Va., females born in 2009 were expected to live to be 74.

At the same time, the study found, the life expectancy gap between black Americans and white Americans is closing. In 1989, black men could expect to live to be 63.8 on average, while white men had an average lifespan of 72.5. In 2009, black male life expectancy improved to 71.2 years, and white male life expectancy improved at a slower rate to 76.7 years. The gap between black women and white women is narrower: Black women on average in 2009 had a life expectancy of 77.9 years, compared to 81.5 years for white women.

Researchers from the University of Washington say variations in life expectancy are often closely tied to socio-economic disparities, with better-educated and more affluent populations more likely to have health insurance and access to quality health care. They also tend to do better in following advice on how best to manage their health.

Researchers say differences in life expectancy often are driven by socioeconomic disparities and access to heath insurance and quality health care.

For example, men and women born in 2009 in Fairfield County were expected to live two years longer than those in New Haven County.